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Texas Instruments ADS7823-28EVM User guides
ADS7823−28 EVM
User’s Guide
June 2004
Data Acquisition Products
SLAU124
IMPORTANT NOTICE
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Mailing Address:
Texas Instruments
Post Office Box 655303 Dallas, Texas 75265
Copyright  2004, Texas Instruments Incorporated
EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided
may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective
considerations, including product safety measures typically found in the end product incorporating the goods.
As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic
compatibility and therefore may not meet the technical requirements of the directive.
Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned
within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE
WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,
IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY
PARTICULAR PURPOSE.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user
indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products
received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction
of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic
discharge.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not
exclusive.
TI assumes no liability for applications assistance, customer product design, software performance, or
infringement of patents or services described herein.
Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM
User’s Guide prior to handling the product. This notice contains important safety information about temperatures
and voltages. For further safety concerns, please contact the TI application engineer.
Persons handling the product must have electronics training and observe good laboratory practice standards.
No license is granted under any patent right or other intellectual property right of TI covering or relating to any
machine, process, or combination in which such TI products or services might be or are used.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright  2004, Texas Instruments Incorporated
EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the input voltage range of 0 - 5 V and the output
voltage range of 0 - 5 V
Exceeding the specified input range may cause unexpected operation and/or irreversible
damage to the EVM. If there are questions concerning the input range, please contact a TI
field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or
possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to
connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than
23°C. The EVM is designed to operate properly with certain components above 23°C as long
as the input and output ranges are maintained. These components include but are not limited
to linear regulators, switching transistors, pass transistors, and current sense resistors. These
types of devices can be identified using the EVM schematic located in the EVM User’s Guide.
When placing measurement probes near these devices during operation, please be aware
that these devices may be very warm to the touch.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright  2004, Texas Instruments Incorporated
Preface
Read This First
About This Manual
This user’s guide describes the characteristics, operation, and use of the
ADS7823- 28 EVM. The ADS7823- 28 is an evaluation module for use with the
12-bit single/octal channel, inter-integrated circuit (I2C) serial interface analog-to-digital converters ADS7823 and ADS7828. Both devices are located on
a single printed wiring board. A complete circuit description as well as a schematic diagram and bill of materials are included.
How to Use This Manual
This document contains the following chapters:
Section 1 – EVM Overview
Section 2 – Analog Interface
Section 3 – Digital Interface
Section 4 – Power Supply Requirements
Section 5 – Board Setup and Operation
Section 6 – EVM BOM and Schematic
FCC Warning
This equipment is intended for use in a laboratory test environment only. It generates, uses, and can radiate radio frequency energy and has not been tested
for compliance with the limits of computing devices pursuant to subpart J of
part 15 of FCC rules, which are designed to provide reasonable protection
against radio frequency interference. Operation of this equipment in other environments may cause interference with radio communications, in which case
the user at his own expense will be required to take whatever measures may
be required to correct this interference.
Trademarks
The I2C protocol is a form of synchronous, 2-wire serial communication developed by Phillips Semiconductors.
Read This First
-5
Related Documentation from Texas Instruments
To obtain a copy of any of the following Texas Instruments documents, call the
Texas Instruments Literature Response Center at (800) 477- 8924 or the Product Information Center (PIC) at (972) 644 - 5580. When ordering, identify this
booklet by the title and literature number. Updated documents can also be obtained through our website at www.ti.com.
-6
Data Sheets:
Literature Number:
ADS7823
SBAS180
ADS7828
SLAS181
5 - 6K Interface Board
SLAU104
DAP Signal Conditioning Boards
SLAU105
Third Party Tools:
Vendor’s Website:
HPA449 Development Board
www.SoftBaugh.com
Contents
1
EVM Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
2
Analog Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1
3
Digital Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
4
Power Supplies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1
Reference Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
5
EVM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.1
Analog Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2
Digital I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.3
Address Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.4
Jumper Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
EVM Bill of Materials and Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1
6.1
Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
6.2
EVM Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
5-1
5-2
5-2
5-2
5-3
Tables
5-1
5-2
6-1
Address Selection Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
Factory Jumper Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
EVM Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
Contents
-7
-8
Chapter 1
EVM Overview
The ADS7823 and ADS7828 are single-supply, low-power, 12-bit data
acquisition devices that feature a serial I2C interface. The ADS7828 also
features an 8-channel multiplexer. The analog-to-digital (A/D) converter
contains a sample-and-hold amplifier and an internal asynchronous clock. The
combination of an I2C serial, 2-wire interface and micropower consumption
makes the ADS7823 and ADS7828 ideal for applications requiring the A/D
converter to be close to the input source in remote locations and for
applications requiring isolation. The EVM features one of each device (the
ADS7823 and ADS7828) installed directly on the board.
Topic
1.1
Page
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
EVM Overview
1-1
Features
1.1 Features
Full - featured evaluation board for the ADS7823 and ADS7828,
single/octal channel analog-to-digital converters with I2C interface
Up to eight single-ended or four differential analog inputs
Built in reference with buffered output
I2C interface
Modular EVM form factor for use with a variety of Texas Instruments
processors and interface boards
1-2
EVM Overview
1-3
Chapter 2
Analog Interface
For maximum flexibility, the ADS7823-28 EVM is designed for easy interfacing
to multiple analog sources. Samtec part numbers SSW - 110 - 22 - F - D - VS - K
and TSM - 110 - 01 - T - DV - P provide a convenient 10-pin dual row header/
socket combination at J1. This header/socket provides access to the analog
input pins of the ADC. Consult Samtec at www.samtec.com or call
1 - 800 - SAMTEC- 9 for a variety of mating connector options.
Pin Number
Signal
Description
J1.2
CH0
MUX input line 0 to ADS7828, AIN to ADS7823
via W4
J1.4
CH 1
MUX input line 1
J1.6
CH 2
MUX input line 2
J1.8
CH 3
MUX input line 3
J1.10
CH 4
MUX input line 4
J1.12
CH 5
MUX input line 5
J1.14
CH 6
MUX input line 6
J1.16
CH 7
MUX input line 7
J1.18
Unused
Pin is unused and should be left open for use with
future amplifier and sensor input modules.
J1.20
REFIN
External reference source input (0 to VDD MAX)
J1.1 - J1.19
(odd)
AGND
Analog ground connections (except J1.15)
J1.15
VCOM Out
BufOut voltage available on this pin by appropriately setting W1
Analog Interface
2-1
2-2
Chapter 3
Digital Interface
The ADS7823-28 EVM is designed for easy interfacing to multiple control
platforms. Samtec part numbers SSW - 110 - 22 - F - D - VS - K and
TSM - 110 - 01 - T - DV - P provide a convenient 10-pin dual row header/socket
combination at J2. This header/socket provides access to the digital control
and serial data pins of the ADS7823 and ADS7828. Consult Samtec at
www.samtec.com or 1 - 800 - SAMTEC- 9 for a variety of mating connector
options.
Pin Number
Signal
Description
J2.1 – J2.19,
J2.2, 6, 8, 12, 14
NC
No connections are associated with these pins.
May be used in conjunction with GPIO source to
control address settings of the ADS7823 and
ADS7828 devices.
J2.16
SCL
Serial clock input to the ADC
J2.18
SDA
Serial data to/from the ADC
J2.4, 10, 18
DGND
Digital ground connections
Digital Interface
3-1
3-2
Chapter 4
Power Supplies
The ADS7823 - 28 EVM board requires +2.7 Vdc to 5.5 Vdc (3.3 V Nom) to
power the ADC. While filters are provided for all power supply inputs, optimal
performance of the EVM requires a clean, well-regulated power source.
Positive 5-V and 3.3-V power is applied to J3 located on the bottom side of the
printed circuit board when used in combination with the 5 - 6K interface or
HPA449 development boards. Jumper W3 allows the user to choose 3.3-V
operation (default) when a shunt is placed across pins 1- 2. Moving the shunt
to pins 2 - 3 allows 5-V operation.
If a variable digital supply voltage is desired, please completely remove the
shunt jumper from W3. Apply a 100-mA current limited dc voltage of not more
than 5.5 V to the test point TP5, referenced to GND (TP3).
Topic
4.1
Page
Reference Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Power Supplies
4-1
Reference Voltage
4.1 Reference Voltage
The ADS7823 - 28 can be configured to use the internal reference of the
ADS7828 or an external reference source through jumper W1 (see the
schematic for details). If an external reference is desired, the shunt jumper on
W1 should cover pins 1 - 2. The external reference is supplied through J1 pin
20. The EVM is factory configured for use with the internal reference (W1 pin
2 - 3).
4-2
Chapter 5
EVM Operation
Apply power to the EVM. For use in combination with one of the modular EVM
interface boards, this is accomplished by simply plugging the ADS7823 - 28
into one of the serial positions (see the interface board schematics/documents
for details). For stand alone use, apply power to TP4 (VDD) referenced to TP3
(GND).
Topic
Page
5.1
Analog Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5.2
Digital I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5.3
Address Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2
5.4
Jumper Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-3
EVM Operation
5-1
Analog Input
5.1 Analog Input
The analog input source can be applied directly to J1 (top or bottom side) or
through optional amplifier and signal conditioning modules. The ADS7823
accepts single-ended input in the range of 0-V ref (5.5 V max). The analog
input to the ADS7823 is shared with channel 0 of the ADS7828 device through
J1 pin 2 and jumper W4.
For the ADS7828, the analog input level should not exceed 5 Vp - p (centered
at 2.5 V) when configured for differential mode operation. The analog input
range is from GND to +VREF (0 V – 5.5 V max) when configured as single
ended inputs. Up to eight single-ended inputs can be applied to connector J2,
pins 2 - 16 (even).
A maximum of four differential inputs may be applied to J2, using pins 2 - 4,
6 - 8, 10- 12, and 14- 16 as differential pair inputs. Single-ended and differential
modes, as well as differential polarity, can be configured by writing to the ADC
Gain/MUX register. Open W4 to remove the analog signal from the input of the
ADS7823 when using differential mode signals.
5.2 Digital I/O
The digital control signals can be applied directly to J2 (top or bottom side). The
ADS7823- 28 EVM can also be connected directly to a DSP or micro controller
interface board such as the 5 - 6K interface board or HPA449 development
board. Consult the ADS7823 and ADS7828 product folders for a complete list
of DSP interface cards, optional analog interface modules, and available
application notes.
5.3 Address Selection
Jumper W2 provides a means to control the I2C address of the ADS7823 and
ADS7828. W2 pins 1 - 2 and 3 - 4 control A0 and A1 respectively of the
ADS7823. W2 pins 5 - 6 and 7 - 8 control A0 and A1 respectively of the
ADS7828.
Table 5 - 1 describes the address selection options for both devices.
Table 5 - 1. Address Selection Options
5-2
W2
Controls
Jumper Functions / I2C Address Restrictions
1-2
ADS7823 – A0
An open jumper places the address pin voltage at VDD
through a 10-kΩ pullup. Closing the jumper places the
address pin at ground potential. Four possible address locations are available for each device. For
proper operation of both devices simultaneously,
each device must have a unique address.
3-4
ADS7823 – A1
5-6
ADS7828 – A0
7-8
ADS7828 – A1
Jumper Defaults
5.4 Jumper Defaults
Table 5 - 2 describes the factory jumper defaults as well as the functions the
jumpers control.
Table 5 - 2. Factory Jumper Defaults
Jumper
Default
Position
Function
W1
Open
Applies internal/common-mode output from/to J1.
Default is neither applied.
W2
1 - 2 and
3 - 4 closed
Sets ADS7823 to address 00 and ADS7828 to address 11
W3
1-2
Applies 3.3 V or 5 V to VDD when using an appropriate
interface board. Default is 3.3 V.
W4
Closed
Applies AIN from J1.1 to ADS7823.
EVM Operation
5-3
5-4
Chapter 6
EVM Bill of Materials and Schematic
This chapter contains the bill of materials table and the schematic diagram.
Topic
Page
6.1
Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2
6.2
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
EVM Bill of Materials and Schematic
6-1
Bill of Materials
6.1 Bill of Materials
Table 6 - 1 contains a complete bill of materials for the ADS7823 - 28 EVM.
Table 6 - 1. EVM Bill of Materials
Designators
Description
Manufacturer
Mfg. Part Number
C1, C2, C3,
C4, C5, C6,
C7, C8, C9,
C10, C11,
C12
Not installed
C14, C19,
C20, C23
1 µF, 0805, ceramic
Panasonic
ECJ - 2YB1H105K
C18
33 µF, 16 V, aluminum, Size C
Cornell Dubilier
AVS106M16B12T
C13, C15,
C17, C21
1 nF, 0805, ceramic, NPO, 50 V, 5%
PhyComp
0805CG102J9B200
C22
10-µF tantalum
FB1
SMT, EMI beads, Z = 47 Ω at 100 MHz
Fair - Rite
2743019447
J1, J2 (top
side)
10-pin, dual row, SMT header (20 Pos.)
Samtec
TSM - 110 - 01 - T - DV - P
J1B, J2B
(bottom side)
10-pin, dual row, SMT socket (20 Pos.)
Samtec
SSW - 110 - 22 - F - D - VS - K
J3
(bottom side)
5-pin, dual row, SMT socket (10 Pos.)
Samtec
SSW - 105 - 22 - F - D - VS - K
R1, R2, R3,
R4, R5, R6,
R7, R8
0 Ω, 0805, 0.1-W resistor
Yageo America
9C08052A0R00JLHFT
R10, R11,
R12, R13,
R14, R15
10 kΩ, 0805, 0.1-W resistor
Yageo America
9C08052A1002JLHFT
TP1, TP4
Red test point loop
Keystone
5000
TP2, TP3
Black test point loop
Keystone
5001
U1
ADS7828
Texas Instruments
ADS7828E
U2
ADS7823
Texas Instruments
ADS7823E
W1, W3
3-pin header
Samtec
TSW - 103 - 07 - L - S
W2
4-pin, dual row, TH header (8 Pos.)
Samtec
TSW - 104 - 07 - L - D
W4
2-pin header
Samtec
TSW - 103 - 07 - L - S
6-2
EVM Schematic
6.2 EVM Schematic
The schematic diagram is also provided for reference.
EVM Bill of Materials and Schematic
6-3
Revision History
REV
ECN Number
Approved
A
Initial Release
TH
J2
D
W4
Vdd
AIN
TP2
U1
User Options
R1
0 ohm
C1
NI
2
C9
3
NI
C2
R2
1
4
NI
0 ohm
5
R3
6
0 ohm
C3
C
C4
J1
1
3
5
7
9
11
13
15
17
19
NI
R4
2
4
6
8
10
12
14
16
18
20
7
NI
8
NI
11
0 ohm
R5
+Vdd
0 ohm
C5
C6
R6
TP1
NI
10
C11
NI
NI
C21
C14
0.01uF
1.0uF
CH2
SDA
CH3
R8
NI
SCL
CH5
A1
CH6
A0
R12
13
12
10K
C
9
REFin/out
ADS7828E
U2
NI
NI
2
AIN
+Vdd
SCL
A1
1
C17
0.01uF
Vdd
TP4
FB1
TP3
C16
0.01uF
+
C18
33uF
8
C15
0.01uF
C20
1.0uF
B
AIN
VCOM_OUT
+3.3V
R11
10K
COM
SDA
+5V
Vdd
CH7
W1
A
SDA
14
CH4
EXT_REF+
2
4
6
8
10
SCL
C12
0 ohm
J3
R10
10K
Vdd
C7
C8
C22
10uF
R9
10K
D
15
0 ohm
R7
+
1
3
5
7
9
16
C19
1.0uF
2
4
6
8
10
12
14
16
18
20
CH1
GND
0 ohm
B
C10
CH0
C13
0.01uF
1
3
5
7
9
11
13
15
17
19
VREF
C23
1.0uF
A0
GND
ADS7823E
6
7
R13
5
3
10K
Vdd
R14
10K
4
7
5
3
1
8
6
4
2
ti
W2
A
12500 TI Blvd. Dallas, Texas 75243
Title:
Tom Hendrick
Tom Hendrick
EDGE #6457911
ADS7823-28 EVM Schematic
Drawn By:
W3
Engineer:
FILE:
SIZE:
B
DATE:
16-Jun-2004
REV:
A
1
SHEET:
OF:
1
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